The statute most frequentThe statute most frequently violated by creditors and their agents is the Fair Debt Collection Practices Act ("FDCPA").  Many debt collectors do not even try to comply with the FDCPA, and just treat the occassional claim or lawsuit for violating the FDCPA as a cost of doing business.

The FDCPA provides that creditors and their agents (i.e., debt collectors) who contact a debtor may not:
-Contact the debtor at an inappropriate time (8 AM - 9 PM is usually    considered appropriate, but state laws may further limit calling hours);
-Contact the debtor at work if creditor or its agent knows that this violates the employer's policy (i.e., employer prohibits personal phone calls);
-Contact the debtor who the creditor knows is represented by counsel;
-Threaten harm to person(s), property or reputation;
-Use foul language or coercion;
-Disclosing the debtor's information to anyone other than those authorized by statute (e.g., credit reporting agencies);
-Repeatedly call the debtor for the purpose of harassment; and 
-Fail to accurately identify themselves when calling.

Creditors and debt collectors must also provide written notice of:
-The amount of the debt;
-The debtor's right to dispute the debt within 30 days, and the failure to promptly dispute resulting in a presumption the debt is valid;
-The debtor's right to receive verification of any debt or judgment entered against the debtor; and
-On request of debtor, the original creditor if the debt was sold.

Creditors and debt collectors when contacting third parties must:
-Accurately identify themselves, and their employer;
-Only attempt to confirm contact information for the debtor;
-Not divulge that the debtor owes money;
-Contact a third party more than once, unless there is a reasonable belief that the third party has been untruthful or has information not previously disclosed; and
-Use postcards or identify on the exterior of any mailing that the correspondence relates to debt collection.

ly violated by creditor